Eir won't release the UAN, phone line still active

The account was in my mother's name who died, we had telephone and broadband services.

We cancel the account via email on the 31st May 2018 and got confirmation on the 1st June saying it be done within 24 hours.

On the 5th June it was still active and phoned up 1901 and was told it be done that day, on the 6th June still active and was told it be done within an hour, on the 7th June still active and was told it be done within 24 hours as waiting for computer etc, yesterday we got an email saying that the account is cancelled but we still have a live phone as can make calls to it and tried dialing out on it to see if it works and does.

We can't phone up 1901 as have to put in either the account number or phone number and saying it is invalid.

They won't release the UAN number so we can switch providers and we can't even switch as the phone line is still active but can't contact eir as you have to put in account number or phone number but saying invalid.

What can we do